Method of heat treating articles



j//f//j/ A. LE 'BOUTILLIER 1,706,725

METHOD OF HEAT TREATING ARTILES March 2K6, 1.9.29.

Filed Feb. 19, 1927 f7 Any Patented Mar. 26, 1929.

UNITED sTATEs 1,706,125 PATENT OFFICE.

AUSTIN LE BOUTILLIER, OF WESTERN SPRINGS, ILLINOIS, ASSIGNOR TO WEST-EBN ELECTRIC COMPANY, INCORPORATED, OF' NEW YORK,

NEW YORK.

N. Y., A CORPORATION OF KETHOD F HEAT TREATING ARTICLES.

Application led February 19, 1927. Serial No. 169,472.

This invention relates to a method of heat treating articles, and more particularly to a method of heat treating thin. flat articles composed of a magnetic nickel iron alloy.

ln the manufacture of apparatus for use in telephone circuits it is necessary to provide verv thin dia hragms made of a'magnetic material an for this purpose thin disks of a'magnetic nickel iron alloy, genphysical characteristics.

" tion,

erally known as perm allov may be employed. One method of making these disks is to sever them from thin latstrips of ermalloy which have previously been eat treated to Fgive them desirable magnetic and However, it has been found ditlicult to heat treat the thin permallo strips without causing the strips to adhere to one another and without causing them to warp or buckle so that they lose their original s ape.

rlhe object of the invention is to provide a simple and effective method of heat treating thin articles.

In carrying out the object of the invenin one embodiment thereof a plurality of articles in the form of thin flat sheets of a magnetic nickel iron alloy are interleaved with a plurality of thin flat plates of silicon steel having an oxide coating on the surfaces thereof. A heavy weight is then placed upon the resulting stack of articles and the articles are heated for a predetermined period of time at a high temperature, after which they are allowed to cool slowly.

@ther objects and features of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawing, in which v Fig. 1 is a vertical sectional view of an apparatus for heat treating articles, with a portion broken away to more clearly illustrate parts thereof, and

Fig. 2 is aneiilarged fragmentary sectional View thereof.

-In the accompanying drawing in which like numerals designate the same parts throughout the several views, the numeral designates generally an annealing furnace by means of which the improved method may be practiced. The furnace 10 comprises a bottom 11, sides 1212, and a to 13 made of a suitable refractor material w ich cooperate to form an annea ing chamber 14. Surrounding the chamber 14 in close proxof thin ,steel having an oxide coating upon the surfaces thereof which is non-adherent to the iniity to the bottom, sides and top thereof, and enclosed within a suitable casing 16, are a pluralit of heating units 15-15 which may be o yany type, such as .electric resistaxice units, well known to the art. A removable box 17 is situated within the chamber 14 and is provided with a removable cover 18, to be which box is designed to hold the articles heat treated. A flat relatively thick steel plate 2() is placed in the bottom of the box 17 and upon this plate are stacked a pluralit of articles 21-21 to be annealed, 1n the orm of thin strips of a nickel iron alloy having a nickel content of more'than 25%, which are interleaved with a plurality flat plat-es 22--22 made of silicon surfaces of the articles at high temperatures. A second comparatively thick fiat late 24;. is placed upon the above mentione( stack of articles and plates and a second stack of articles and interleaved plates are placed upon the plate 24. Any stacks of the articles and the interspersed plates may be used, the draw-ing showing three of such stacks, and u on the top stack are placed a plurality of eavy flat plates 2(`y'-2.

The o eration of the ap iaratus is as follows: A ter the articles an plates have been stacked in the box 17 as described above, the cover 18 is placed upon the box 17, the loaded box placed within the chamber 14 of desired number ofthe annealing furnace 10 and the doors of the chamber (not shown) are closed. The heating units 15--15 are putint-o operation to raise the temperature of the chamber and the enclosed articles to the desired temperature, which in the case of the nickel iron alloys described is within the temperature range of 1650 to 1900 F. retained at the desired temperature for a predetermined period of time, depending upon the characteristics desired For the articular articles described above, one hour as proven asatisfactory heating eriod. After the articles are heated for the d length of time, the box 17 containing the articles is removed from the annealing furnace 10 and the articles are allowed to cool4 The articles are f esired 'fnealing process, whilel the pressure exerted by the Wei ht of the heavy plates placed upon the stac s of articles causes the articles to assume and retain the llatness desired in the finished product. It is evident, however, that the process may be employed equally Well with articles having irregular surfaces by providing plates 22-22 having corresponding surfaces and the Weight of the plates 26-26 will then tend to retain the articles in their original shape.

What is claimed is:

1. A process for heat treating articles, which consists in interleaving a. plurality of the articles with a plurality of thin plates having thereon a surface layer of material which is non-adherent to the articles at high tem eratures, applying pressure to the re sultln stack, and heating the articles.

2. process for heat treating thin articles, which consists in interleaving a plurality of the articles with a plurality of thin plates composed of a material having an oxide coating thereon, applying pressure to the resulting stack, heating the articles at a high temperature, and slowly cooling the ar ticles.

3. A process for heat treating thin articles composed of a nickel-iron alloy, which con- 'sists in interleaving a plurality of the ar ticles with a plurality of silicon steel plates having a surface scale thereon to prevent weaves adherence of the articles, and heating the resulting stack to a'minimum temperature 0f 16500 F.

l 4. A process for heat treating thin iiat articles composed of a magnetic nicliel-iron alloy, which consists in interleaving a plu rality of the articles with a plurality of thin flat plates of silicon steel having an oxide coating thereon to prevent adherence of the articles, applying pressure to the resulting stack to maintain the fiatness of the articles, and heating the articles for a predetermined period of time within the temperature range to 1650o to 1900O F. l

5. A process 'for heat treating thin flat articles composed of a magnetic nickel-iron alloy, which consists in interleaving a plu rality lot the articles with a plurality of thin flat plates of silicon steel having an oxide coating thereon to prevent adherence of the articles, applying pressure to the resulting stack to maintain the ilatness of the articles,lieating the articles for about one hour within the temperature range of 1,650 to 1900o F., and slowly cooling the articles.

6. A process for annealing metallic sheets at high temperatures, which includes interleaving tlie metallic sheets with metallic plates having an oxide scale t0 prevent the metallic sheets from becoming welded together, and subjecting the interleaved an ticles to heat.

In Witness whereof, I hereunto subscribe my name this 2nd day of February, A. D.

AUSTIN LE BUTILLEER. 

